1. Introduction -- 2. The crisis of succession. The Saqīfah Debate and its aftermath -- 3. Abū Bakr's regrets and ʻUmar's uncertainties. Abū Bakr: Khalīfat Rasūl Allāh. ʻUmar: Amīr al-Muʼminīn -- 4. The second crisis: the Shūrā Council and its failure. The Shūrā deliberations -- 5. ʻUthmān: Khalīfat Allāh. ʻUthmān's caliphate: Umayyad power and the beginning of Shīʻī opposition. ʻUthmān's critics: ʻAmmār b. Yāsir and Abū Dharr al-Ghifārī. ʻUthmān and the clash between religious authority and political power. The siege and ʻUthmān's violent death -- 6. ʻAli Waṣī Rasūl Allāh: the clash of religion and politics. The battle of the camel. Muʻāwiyah's opposition. The battle of Ṣiffīn. ʻAmr's scheme and its consequences. The collapse of ʻAlī's rule and the end of the normative caliphate -- 7. Conclusion -- Appendix I. The four "rightly guided" caliphs in their own words -- Appendix II. The Ṣiffīn truce document -- Bibliography